Jessie J has had a remarkably eventful 2011. Having started the year an unknown, the woman born Jessie Cornish has scooped the Brits' critics award and, bizarrely, four Mobos, seen her debut album Who You Are go double-platinum, broken her foot and spent subsequent weeks putting it in her mouth, not least in a recent interview, where she claimed her mishap had "given her a different respect for people who don't have legs".

Her success is surprising, as Who You Are is a wretched record, a farrago of gratingly banal dance-pop and overwrought sub-X Factor balladry. Yet Jessie J comes into her own live. Strapped into a skimpy purple bondage costume like a Primark Cleopatra, she turns in an exuberant, personality-plus performance that succeeds in temporarily distracting you from the awfulness of her material.

An Amazonian figure skipping across a lavish blood-red set, she dispatches saccharine power ballads such as Casualty of Love and Not Perfect in a foghorn blare. When James Morrison joins her for the raucous pop-soul of Up, she dwarfs him in stature and charisma, as Morrison gamely attempts to boogie on down before gratefully exiting after the pair share an excruciating high-five.

The new material previewed is deeply unprepossessing: My Shadow is a vocal gymnastic exercise that Celine Dion would reject as overly mawkish, while Technology poses the deathless question "Was it real, or just a re-tweet?" She's on safer ground with the encore of her two stuttering electro-pop hits, Do It Like a Dude and Price Tag, which encapsulate Jessie J perfectly: a hyper-modern triumph of chutzpah, and of spirited mediocrity.